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From: litter AT null DOT net
To: cygwin AT cygwin DOT com
In-Reply-To: 663517E1C874873ADB12BADE23DA8EB9
Subject: Re: Bash / cygwin process spawning (?) performance very slow
Message-ID: <5602C4AD.2060609@null.net>
Date: Wed, 23 Sep 2015 17:26:37 +0200
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> litter AT null DOT net:
> Wed, 23 Sep 2015 10:52:26 +0200
> ---------------------------------------------------
>> Hi all,
>> 
>> I noticed that doing simple loops in Bash takes unexpectedly long under Cygwin on a Windows XP 32 bit machine 
>> (CYGWIN_NT-5.1 <machine> 2.2.1(0.289/5/3) 2015-08-20 11:40 i686 Cygwin)
>> 
>> I already followed the FAQ advice in trying to determine general causes, and made a 'shadow' copy of /etc/passwd as described.
>> My PATH does not contain references to network shares.
>> 
>> Still quite normal commands take a long time e.g. 
>> time cat some-file | while read i;do echo $i;/bin/true;done
>> 
>> real 1m44.953s
>> user 0m9.599s
>> sys 1m36.865s
> 
> #wc t; time cat t  | while read i;do echo $i;/bin/true;done >/dev/null
>  172  172 3448 t
>     3.73s real     0.04s user     0.43s system
> 
> On cygwin 1.7.35 and XP32. Not THAT fast but similar to your 
> linux-result. I guess your antivirus is interfering. I've configured 
> my avast to not deep-scan anything in C:\cygwin\bin, maybe that helps.
> 
> -Helmut

Thanks for the reply Helmut,

Although the /dev/null probably contributes a bit to the timing
it's clear not all 32 bit XP systems suffer from this, thanks for that!

I'm not running any antivirus as far as I'm aware of (I do run a Comodo firewall with all "virus" scanning disabled).
I checked again, and it really is the Bash.exe which is consuming a lot of Kernel time. I didn't spot another process kicking in and consuming cycles.

Any idea how to diagnose the cause of this? Is there any Cygwin specific logging/tracing to see where it is happening?

Thanks,
Paul


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